We propose to obtain a more comprehensive view of the structure and specificity of RNA polymerase during growth and differentiation of Bacillus subtilis by a series of genetic and biochemical experiments designed to elucidate the role played by individual components of the enzyme in controlling transcription. Our basic approach will be to study the properties of mutant strains that we have already isolated and plan to isolate which are likely to bear lesions in components of the transcriptional apparatus. By examining the molecular mechanism responsible for inability of a particular mutant to grow, to sporulate or to germinate, we expect to deduce some of the mechanisms by which wild-type strains control differentiation. In addition, we propose to measure the rates of synthesis of specific messenger RNA's during growth and sporulation.